/*
 * PCI Stub Driver - Grabs devices in backend to be exported later
 *
 * Ryan Wilson <hap9@epoch.ncsc.mil>
 * Chris Bookholt <hap10@epoch.ncsc.mil>
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rwsem.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/kref.h>
#include <linux/pci.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/atomic.h>
#include <xen/events.h>
#include <asm/xen/pci.h>
#include <asm/xen/hypervisor.h>
#include "pciback.h"
#include "conf_space.h"
#include "conf_space_quirks.h"

static char *pci_devs_to_hide;
wait_queue_head_t xen_pcibk_aer_wait_queue;
/*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
* We want to avoid in middle of AER ops, xen_pcibk devices is being removed
*/
static DECLARE_RWSEM(pcistub_sem);
module_param_named(hide, pci_devs_to_hide, charp, 0444);

struct pcistub_device_id {
        struct list_head slot_list;
        int domain;
        unsigned char bus;
        unsigned int devfn;
};
static LIST_HEAD(pcistub_device_ids);
static DEFINE_SPINLOCK(device_ids_lock);

struct pcistub_device {
        struct kref kref;
        struct list_head dev_list;
        spinlock_t lock;

        struct pci_dev *dev;
        struct xen_pcibk_device *pdev;/* non-NULL if struct pci_dev is in use */
};

/* Access to pcistub_devices & seized_devices lists and the initialize_devices
 * flag must be locked with pcistub_devices_lock
 */
static DEFINE_SPINLOCK(pcistub_devices_lock);
static LIST_HEAD(pcistub_devices);

/* wait for device_initcall before initializing our devices
 * (see pcistub_init_devices_late)
 */
static int initialize_devices;
static LIST_HEAD(seized_devices);

static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev)
{
        struct pcistub_device *psdev;

        dev_dbg(&dev->dev, "pcistub_device_alloc\n");

        psdev = kzalloc(sizeof(*psdev), GFP_ATOMIC);
        if (!psdev)
                return NULL;

        psdev->dev = pci_dev_get(dev);
        if (!psdev->dev) {
                kfree(psdev);
                return NULL;
        }

        kref_init(&psdev->kref);
        spin_lock_init(&psdev->lock);

        return psdev;
}

/* Don't call this directly as it's called by pcistub_device_put */
static void pcistub_device_release(struct kref *kref)
{
        struct pcistub_device *psdev;
        struct xen_pcibk_dev_data *dev_data;

        psdev = container_of(kref, struct pcistub_device, kref);
        dev_data = pci_get_drvdata(psdev->dev);

        dev_dbg(&psdev->dev->dev, "pcistub_device_release\n");

        xen_unregister_device_domain_owner(psdev->dev);

        /* Call the reset function which does not take lock as this
         * is called from "unbind" which takes a device_lock mutex.
         */
        __pci_reset_function_locked(psdev->dev);
        if (pci_load_and_free_saved_state(psdev->dev,
                                          &dev_data->pci_saved_state)) {
                dev_dbg(&psdev->dev->dev, "Could not reload PCI state\n");
        } else
                pci_restore_state(psdev->dev);

        /* Disable the device */
        xen_pcibk_reset_device(psdev->dev);

        kfree(dev_data);
        pci_set_drvdata(psdev->dev, NULL);

        /* Clean-up the device */
        xen_pcibk_config_free_dyn_fields(psdev->dev);
        xen_pcibk_config_free_dev(psdev->dev);

        psdev->dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
        pci_dev_put(psdev->dev);

        kfree(psdev);
}

static inline void pcistub_device_get(struct pcistub_device *psdev)
{
        kref_get(&psdev->kref);
}

static inline void pcistub_device_put(struct pcistub_device *psdev)
{
        kref_put(&psdev->kref, pcistub_device_release);
}

static struct pcistub_device *pcistub_device_find(int domain, int bus,
                                                  int slot, int func)
{
        struct pcistub_device *psdev = NULL;
        unsigned long flags;

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (psdev->dev != NULL
                    && domain == pci_domain_nr(psdev->dev->bus)
                    && bus == psdev->dev->bus->number
                    && PCI_DEVFN(slot, func) == psdev->dev->devfn) {
                        pcistub_device_get(psdev);
                        goto out;
                }
        }

        /* didn't find it */
        psdev = NULL;

out:
        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
        return psdev;
}

static struct pci_dev *pcistub_device_get_pci_dev(struct xen_pcibk_device *pdev,
                                                  struct pcistub_device *psdev)
{
        struct pci_dev *pci_dev = NULL;
        unsigned long flags;

        pcistub_device_get(psdev);

        spin_lock_irqsave(&psdev->lock, flags);
        if (!psdev->pdev) {
                psdev->pdev = pdev;
                pci_dev = psdev->dev;
        }
        spin_unlock_irqrestore(&psdev->lock, flags);

        if (!pci_dev)
                pcistub_device_put(psdev);

        return pci_dev;
}

struct pci_dev *pcistub_get_pci_dev_by_slot(struct xen_pcibk_device *pdev,
                                            int domain, int bus,
                                            int slot, int func)
{
        struct pcistub_device *psdev;
        struct pci_dev *found_dev = NULL;
        unsigned long flags;

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (psdev->dev != NULL
                    && domain == pci_domain_nr(psdev->dev->bus)
                    && bus == psdev->dev->bus->number
                    && PCI_DEVFN(slot, func) == psdev->dev->devfn) {
                        found_dev = pcistub_device_get_pci_dev(pdev, psdev);
                        break;
                }
        }

        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
        return found_dev;
}

struct pci_dev *pcistub_get_pci_dev(struct xen_pcibk_device *pdev,
                                    struct pci_dev *dev)
{
        struct pcistub_device *psdev;
        struct pci_dev *found_dev = NULL;
        unsigned long flags;

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (psdev->dev == dev) {
                        found_dev = pcistub_device_get_pci_dev(pdev, psdev);
                        break;
                }
        }

        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
        return found_dev;
}

void pcistub_put_pci_dev(struct pci_dev *dev)
{
        struct pcistub_device *psdev, *found_psdev = NULL;
        unsigned long flags;

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (psdev->dev == dev) {
                        found_psdev = psdev;
                        break;
                }
        }

        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
        if (WARN_ON(!found_psdev))
                return;

        /*hold this lock for avoiding breaking link between
        * pcistub and xen_pcibk when AER is in processing
        */
        down_write(&pcistub_sem);
        /* Cleanup our device
         * (so it's ready for the next domain)
         */

        /* This is OK - we are running from workqueue context
         * and want to inhibit the user from fiddling with 'reset'
         */
        pci_reset_function(dev);
        pci_restore_state(psdev->dev);

        /* This disables the device. */
        xen_pcibk_reset_device(found_psdev->dev);

        /* And cleanup up our emulated fields. */
        xen_pcibk_config_free_dyn_fields(found_psdev->dev);
        xen_pcibk_config_reset_dev(found_psdev->dev);

        xen_unregister_device_domain_owner(found_psdev->dev);

        spin_lock_irqsave(&found_psdev->lock, flags);
        found_psdev->pdev = NULL;
        spin_unlock_irqrestore(&found_psdev->lock, flags);

        pcistub_device_put(found_psdev);
        up_write(&pcistub_sem);
}

static int __devinit pcistub_match_one(struct pci_dev *dev,
                                       struct pcistub_device_id *pdev_id)
{
        /* Match the specified device by domain, bus, slot, func and also if
         * any of the device's parent bridges match.
         */
        for (; dev != NULL; dev = dev->bus->self) {
                if (pci_domain_nr(dev->bus) == pdev_id->domain
                    && dev->bus->number == pdev_id->bus
                    && dev->devfn == pdev_id->devfn)
                        return 1;

                /* Sometimes topmost bridge links to itself. */
                if (dev == dev->bus->self)
                        break;
        }

        return 0;
}

static int __devinit pcistub_match(struct pci_dev *dev)
{
        struct pcistub_device_id *pdev_id;
        unsigned long flags;
        int found = 0;

        spin_lock_irqsave(&device_ids_lock, flags);
        list_for_each_entry(pdev_id, &pcistub_device_ids, slot_list) {
                if (pcistub_match_one(dev, pdev_id)) {
                        found = 1;
                        break;
                }
        }
        spin_unlock_irqrestore(&device_ids_lock, flags);

        return found;
}

static int __devinit pcistub_init_device(struct pci_dev *dev)
{
        struct xen_pcibk_dev_data *dev_data;
        int err = 0;

        dev_dbg(&dev->dev, "initializing...\n");

        /* The PCI backend is not intended to be a module (or to work with
         * removable PCI devices (yet). If it were, xen_pcibk_config_free()
         * would need to be called somewhere to free the memory allocated
         * here and then to call kfree(pci_get_drvdata(psdev->dev)).
         */
        dev_data = kzalloc(sizeof(*dev_data) +  strlen(DRV_NAME "[]")
                                + strlen(pci_name(dev)) + 1, GFP_ATOMIC);
        if (!dev_data) {
                err = -ENOMEM;
                goto out;
        }
        pci_set_drvdata(dev, dev_data);

        /*
         * Setup name for fake IRQ handler. It will only be enabled
         * once the device is turned on by the guest.
         */
        sprintf(dev_data->irq_name, DRV_NAME "[%s]", pci_name(dev));

        dev_dbg(&dev->dev, "initializing config\n");

        init_waitqueue_head(&xen_pcibk_aer_wait_queue);
        err = xen_pcibk_config_init_dev(dev);
        if (err)
                goto out;

        /* HACK: Force device (& ACPI) to determine what IRQ it's on - we
         * must do this here because pcibios_enable_device may specify
         * the pci device's true irq (and possibly its other resources)
         * if they differ from what's in the configuration space.
         * This makes the assumption that the device's resources won't
         * change after this point (otherwise this code may break!)
         */
        dev_dbg(&dev->dev, "enabling device\n");
        err = pci_enable_device(dev);
        if (err)
                goto config_release;

        dev_dbg(&dev->dev, "reseting (FLR, D3, etc) the device\n");
        __pci_reset_function_locked(dev);

        /* We need the device active to save the state. */
        dev_dbg(&dev->dev, "save state of device\n");
        pci_save_state(dev);
        dev_data->pci_saved_state = pci_store_saved_state(dev);
        if (!dev_data->pci_saved_state)
                dev_err(&dev->dev, "Could not store PCI conf saved state!\n");

        /* Now disable the device (this also ensures some private device
         * data is setup before we export)
         */
        dev_dbg(&dev->dev, "reset device\n");
        xen_pcibk_reset_device(dev);

        dev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
        return 0;

config_release:
        xen_pcibk_config_free_dev(dev);

out:
        pci_set_drvdata(dev, NULL);
        kfree(dev_data);
        return err;
}

/*
 * Because some initialization still happens on
 * devices during fs_initcall, we need to defer
 * full initialization of our devices until
 * device_initcall.
 */
static int __init pcistub_init_devices_late(void)
{
        struct pcistub_device *psdev;
        unsigned long flags;
        int err = 0;

        pr_debug(DRV_NAME ": pcistub_init_devices_late\n");

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        while (!list_empty(&seized_devices)) {
                psdev = container_of(seized_devices.next,
                                     struct pcistub_device, dev_list);
                list_del(&psdev->dev_list);

                spin_unlock_irqrestore(&pcistub_devices_lock, flags);

                err = pcistub_init_device(psdev->dev);
                if (err) {
                        dev_err(&psdev->dev->dev,
                                "error %d initializing device\n", err);
                        kfree(psdev);
                        psdev = NULL;
                }

                spin_lock_irqsave(&pcistub_devices_lock, flags);

                if (psdev)
                        list_add_tail(&psdev->dev_list, &pcistub_devices);
        }

        initialize_devices = 1;

        spin_unlock_irqrestore(&pcistub_devices_lock, flags);

        return 0;
}

static int __devinit pcistub_seize(struct pci_dev *dev)
{
        struct pcistub_device *psdev;
        unsigned long flags;
        int err = 0;

        psdev = pcistub_device_alloc(dev);
        if (!psdev)
                return -ENOMEM;

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        if (initialize_devices) {
                spin_unlock_irqrestore(&pcistub_devices_lock, flags);

                /* don't want irqs disabled when calling pcistub_init_device */
                err = pcistub_init_device(psdev->dev);

                spin_lock_irqsave(&pcistub_devices_lock, flags);

                if (!err)
                        list_add(&psdev->dev_list, &pcistub_devices);
        } else {
                dev_dbg(&dev->dev, "deferring initialization\n");
                list_add(&psdev->dev_list, &seized_devices);
        }

        spin_unlock_irqrestore(&pcistub_devices_lock, flags);

        if (err)
                pcistub_device_put(psdev);

        return err;
}

static int __devinit pcistub_probe(struct pci_dev *dev,
                                   const struct pci_device_id *id)
{
        int err = 0;

        dev_dbg(&dev->dev, "probing...\n");

        if (pcistub_match(dev)) {

                if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL
                    && dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
                        dev_err(&dev->dev, "can't export pci devices that "
                                "don't have a normal (0) or bridge (1) "
                                "header type!\n");
                        err = -ENODEV;
                        goto out;
                }

                dev_info(&dev->dev, "seizing device\n");
                err = pcistub_seize(dev);
        } else
                /* Didn't find the device */
                err = -ENODEV;

out:
        return err;
}

static void pcistub_remove(struct pci_dev *dev)
{
        struct pcistub_device *psdev, *found_psdev = NULL;
        unsigned long flags;

        dev_dbg(&dev->dev, "removing\n");

        spin_lock_irqsave(&pcistub_devices_lock, flags);

        xen_pcibk_config_quirk_release(dev);

        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (psdev->dev == dev) {
                        found_psdev = psdev;
                        break;
                }
        }

        spin_unlock_irqrestore(&pcistub_devices_lock, flags);

        if (found_psdev) {
                dev_dbg(&dev->dev, "found device to remove - in use? %p\n",
                        found_psdev->pdev);

                if (found_psdev->pdev) {
                        printk(KERN_WARNING DRV_NAME ": ****** removing device "
                               "%s while still in-use! ******\n",
                               pci_name(found_psdev->dev));
                        printk(KERN_WARNING DRV_NAME ": ****** driver domain may"
                               " still access this device's i/o resources!\n");
                        printk(KERN_WARNING DRV_NAME ": ****** shutdown driver "
                               "domain before binding device\n");
                        printk(KERN_WARNING DRV_NAME ": ****** to other drivers "
                               "or domains\n");

                        xen_pcibk_release_pci_dev(found_psdev->pdev,
                                                found_psdev->dev);
                }

                spin_lock_irqsave(&pcistub_devices_lock, flags);
                list_del(&found_psdev->dev_list);
                spin_unlock_irqrestore(&pcistub_devices_lock, flags);

                /* the final put for releasing from the list */
                pcistub_device_put(found_psdev);
        }
}

static DEFINE_PCI_DEVICE_TABLE(pcistub_ids) = {
        {
         .vendor = PCI_ANY_ID,
         .device = PCI_ANY_ID,
         .subvendor = PCI_ANY_ID,
         .subdevice = PCI_ANY_ID,
         },
        {0,},
};

#define PCI_NODENAME_MAX 40
static void kill_domain_by_device(struct pcistub_device *psdev)
{
        struct xenbus_transaction xbt;
        int err;
        char nodename[PCI_NODENAME_MAX];

        BUG_ON(!psdev);
        snprintf(nodename, PCI_NODENAME_MAX, "/local/domain/0/backend/pci/%d/0",
                psdev->pdev->xdev->otherend_id);

again:
        err = xenbus_transaction_start(&xbt);
        if (err) {
                dev_err(&psdev->dev->dev,
                        "error %d when start xenbus transaction\n", err);
                return;
        }
        /*PV AER handlers will set this flag*/
        xenbus_printf(xbt, nodename, "aerState" , "aerfail");
        err = xenbus_transaction_end(xbt, 0);
        if (err) {
                if (err == -EAGAIN)
                        goto again;
                dev_err(&psdev->dev->dev,
                        "error %d when end xenbus transaction\n", err);
                return;
        }
}

/* For each aer recovery step error_detected, mmio_enabled, etc, front_end and
 * backend need to have cooperation. In xen_pcibk, those steps will do similar
 * jobs: send service request and waiting for front_end response.
*/
static pci_ers_result_t common_process(struct pcistub_device *psdev,
                                       pci_channel_state_t state, int aer_cmd,
                                       pci_ers_result_t result)
{
        pci_ers_result_t res = result;
        struct xen_pcie_aer_op *aer_op;
        int ret;

        /*with PV AER drivers*/
        aer_op = &(psdev->pdev->sh_info->aer_op);
        aer_op->cmd = aer_cmd ;
        /*useful for error_detected callback*/
        aer_op->err = state;
        /*pcifront_end BDF*/
        ret = xen_pcibk_get_pcifront_dev(psdev->dev, psdev->pdev,
                &aer_op->domain, &aer_op->bus, &aer_op->devfn);
        if (!ret) {
                dev_err(&psdev->dev->dev,
                        DRV_NAME ": failed to get pcifront device\n");
                return PCI_ERS_RESULT_NONE;
        }
        wmb();

        dev_dbg(&psdev->dev->dev,
                        DRV_NAME ": aer_op %x dom %x bus %x devfn %x\n",
                        aer_cmd, aer_op->domain, aer_op->bus, aer_op->devfn);
        /*local flag to mark there's aer request, xen_pcibk callback will use
        * this flag to judge whether we need to check pci-front give aer
        * service ack signal
        */
        set_bit(_PCIB_op_pending, (unsigned long *)&psdev->pdev->flags);

        /*It is possible that a pcifront conf_read_write ops request invokes
        * the callback which cause the spurious execution of wake_up.
        * Yet it is harmless and better than a spinlock here
        */
        set_bit(_XEN_PCIB_active,
                (unsigned long *)&psdev->pdev->sh_info->flags);
        wmb();
        notify_remote_via_irq(psdev->pdev->evtchn_irq);

        ret = wait_event_timeout(xen_pcibk_aer_wait_queue,
                                 !(test_bit(_XEN_PCIB_active, (unsigned long *)
                                 &psdev->pdev->sh_info->flags)), 300*HZ);

        if (!ret) {
                if (test_bit(_XEN_PCIB_active,
                        (unsigned long *)&psdev->pdev->sh_info->flags)) {
                        dev_err(&psdev->dev->dev,
                                "pcifront aer process not responding!\n");
                        clear_bit(_XEN_PCIB_active,
                          (unsigned long *)&psdev->pdev->sh_info->flags);
                        aer_op->err = PCI_ERS_RESULT_NONE;
                        return res;
                }
        }
        clear_bit(_PCIB_op_pending, (unsigned long *)&psdev->pdev->flags);

        if (test_bit(_XEN_PCIF_active,
                (unsigned long *)&psdev->pdev->sh_info->flags)) {
                dev_dbg(&psdev->dev->dev,
                        "schedule pci_conf service in " DRV_NAME "\n");
                xen_pcibk_test_and_schedule_op(psdev->pdev);
        }

        res = (pci_ers_result_t)aer_op->err;
        return res;
}

/*
* xen_pcibk_slot_reset: it will send the slot_reset request to  pcifront in case
* of the device driver could provide this service, and then wait for pcifront
* ack.
* @dev: pointer to PCI devices
* return value is used by aer_core do_recovery policy
*/
static pci_ers_result_t xen_pcibk_slot_reset(struct pci_dev *dev)
{
        struct pcistub_device *psdev;
        pci_ers_result_t result;

        result = PCI_ERS_RESULT_RECOVERED;
        dev_dbg(&dev->dev, "xen_pcibk_slot_reset(bus:%x,devfn:%x)\n",
                dev->bus->number, dev->devfn);

        down_write(&pcistub_sem);
        psdev = pcistub_device_find(pci_domain_nr(dev->bus),
                                dev->bus->number,
                                PCI_SLOT(dev->devfn),
                                PCI_FUNC(dev->devfn));

        if (!psdev || !psdev->pdev) {
                dev_err(&dev->dev,
                        DRV_NAME " device is not found/assigned\n");
                goto end;
        }

        if (!psdev->pdev->sh_info) {
                dev_err(&dev->dev, DRV_NAME " device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
                goto release;
        }

        if (!test_bit(_XEN_PCIB_AERHANDLER,
                (unsigned long *)&psdev->pdev->sh_info->flags)) {
                dev_err(&dev->dev,
                        "guest with no AER driver should have been killed\n");
                goto release;
        }
        result = common_process(psdev, 1, XEN_PCI_OP_aer_slotreset, result);

        if (result == PCI_ERS_RESULT_NONE ||
                result == PCI_ERS_RESULT_DISCONNECT) {
                dev_dbg(&dev->dev,
                        "No AER slot_reset service or disconnected!\n");
                kill_domain_by_device(psdev);
        }
release:
        pcistub_device_put(psdev);
end:
        up_write(&pcistub_sem);
        return result;

}


/*xen_pcibk_mmio_enabled: it will send the mmio_enabled request to  pcifront
* in case of the device driver could provide this service, and then wait
* for pcifront ack
* @dev: pointer to PCI devices
* return value is used by aer_core do_recovery policy
*/

static pci_ers_result_t xen_pcibk_mmio_enabled(struct pci_dev *dev)
{
        struct pcistub_device *psdev;
        pci_ers_result_t result;

        result = PCI_ERS_RESULT_RECOVERED;
        dev_dbg(&dev->dev, "xen_pcibk_mmio_enabled(bus:%x,devfn:%x)\n",
                dev->bus->number, dev->devfn);

        down_write(&pcistub_sem);
        psdev = pcistub_device_find(pci_domain_nr(dev->bus),
                                dev->bus->number,
                                PCI_SLOT(dev->devfn),
                                PCI_FUNC(dev->devfn));

        if (!psdev || !psdev->pdev) {
                dev_err(&dev->dev,
                        DRV_NAME " device is not found/assigned\n");
                goto end;
        }

        if (!psdev->pdev->sh_info) {
                dev_err(&dev->dev, DRV_NAME " device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
                goto release;
        }

        if (!test_bit(_XEN_PCIB_AERHANDLER,
                (unsigned long *)&psdev->pdev->sh_info->flags)) {
                dev_err(&dev->dev,
                        "guest with no AER driver should have been killed\n");
                goto release;
        }
        result = common_process(psdev, 1, XEN_PCI_OP_aer_mmio, result);

        if (result == PCI_ERS_RESULT_NONE ||
                result == PCI_ERS_RESULT_DISCONNECT) {
                dev_dbg(&dev->dev,
                        "No AER mmio_enabled service or disconnected!\n");
                kill_domain_by_device(psdev);
        }
release:
        pcistub_device_put(psdev);
end:
        up_write(&pcistub_sem);
        return result;
}

/*xen_pcibk_error_detected: it will send the error_detected request to  pcifront
* in case of the device driver could provide this service, and then wait
* for pcifront ack.
* @dev: pointer to PCI devices
* @error: the current PCI connection state
* return value is used by aer_core do_recovery policy
*/

static pci_ers_result_t xen_pcibk_error_detected(struct pci_dev *dev,
        pci_channel_state_t error)
{
        struct pcistub_device *psdev;
        pci_ers_result_t result;

        result = PCI_ERS_RESULT_CAN_RECOVER;
        dev_dbg(&dev->dev, "xen_pcibk_error_detected(bus:%x,devfn:%x)\n",
                dev->bus->number, dev->devfn);

        down_write(&pcistub_sem);
        psdev = pcistub_device_find(pci_domain_nr(dev->bus),
                                dev->bus->number,
                                PCI_SLOT(dev->devfn),
                                PCI_FUNC(dev->devfn));

        if (!psdev || !psdev->pdev) {
                dev_err(&dev->dev,
                        DRV_NAME " device is not found/assigned\n");
                goto end;
        }

        if (!psdev->pdev->sh_info) {
                dev_err(&dev->dev, DRV_NAME " device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
                goto release;
        }

        /*Guest owns the device yet no aer handler regiested, kill guest*/
        if (!test_bit(_XEN_PCIB_AERHANDLER,
                (unsigned long *)&psdev->pdev->sh_info->flags)) {
                dev_dbg(&dev->dev, "guest may have no aer driver, kill it\n");
                kill_domain_by_device(psdev);
                goto release;
        }
        result = common_process(psdev, error, XEN_PCI_OP_aer_detected, result);

        if (result == PCI_ERS_RESULT_NONE ||
                result == PCI_ERS_RESULT_DISCONNECT) {
                dev_dbg(&dev->dev,
                        "No AER error_detected service or disconnected!\n");
                kill_domain_by_device(psdev);
        }
release:
        pcistub_device_put(psdev);
end:
        up_write(&pcistub_sem);
        return result;
}

/*xen_pcibk_error_resume: it will send the error_resume request to  pcifront
* in case of the device driver could provide this service, and then wait
* for pcifront ack.
* @dev: pointer to PCI devices
*/

static void xen_pcibk_error_resume(struct pci_dev *dev)
{
        struct pcistub_device *psdev;

        dev_dbg(&dev->dev, "xen_pcibk_error_resume(bus:%x,devfn:%x)\n",
                dev->bus->number, dev->devfn);

        down_write(&pcistub_sem);
        psdev = pcistub_device_find(pci_domain_nr(dev->bus),
                                dev->bus->number,
                                PCI_SLOT(dev->devfn),
                                PCI_FUNC(dev->devfn));

        if (!psdev || !psdev->pdev) {
                dev_err(&dev->dev,
                        DRV_NAME " device is not found/assigned\n");
                goto end;
        }

        if (!psdev->pdev->sh_info) {
                dev_err(&dev->dev, DRV_NAME " device is not connected or owned"
                        " by HVM, kill it\n");
                kill_domain_by_device(psdev);
                goto release;
        }

        if (!test_bit(_XEN_PCIB_AERHANDLER,
                (unsigned long *)&psdev->pdev->sh_info->flags)) {
                dev_err(&dev->dev,
                        "guest with no AER driver should have been killed\n");
                kill_domain_by_device(psdev);
                goto release;
        }
        common_process(psdev, 1, XEN_PCI_OP_aer_resume,
                       PCI_ERS_RESULT_RECOVERED);
release:
        pcistub_device_put(psdev);
end:
        up_write(&pcistub_sem);
        return;
}

/*add xen_pcibk AER handling*/
static struct pci_error_handlers xen_pcibk_error_handler = {
        .error_detected = xen_pcibk_error_detected,
        .mmio_enabled = xen_pcibk_mmio_enabled,
        .slot_reset = xen_pcibk_slot_reset,
        .resume = xen_pcibk_error_resume,
};

/*
 * Note: There is no MODULE_DEVICE_TABLE entry here because this isn't
 * for a normal device. I don't want it to be loaded automatically.
 */

static struct pci_driver xen_pcibk_pci_driver = {
        /* The name should be xen_pciback, but until the tools are updated
         * we will keep it as pciback. */
        .name = "pciback",
        .id_table = pcistub_ids,
        .probe = pcistub_probe,
        .remove = pcistub_remove,
        .err_handler = &xen_pcibk_error_handler,
};

static inline int str_to_slot(const char *buf, int *domain, int *bus,
                              int *slot, int *func)
{
        int err;

        err = sscanf(buf, " %x:%x:%x.%x", domain, bus, slot, func);
        if (err == 4)
                return 0;
        else if (err < 0)
                return -EINVAL;

        /* try again without domain */
        *domain = 0;
        err = sscanf(buf, " %x:%x.%x", bus, slot, func);
        if (err == 3)
                return 0;

        return -EINVAL;
}

static inline int str_to_quirk(const char *buf, int *domain, int *bus, int
                               *slot, int *func, int *reg, int *size, int *mask)
{
        int err;

        err =
            sscanf(buf, " %04x:%02x:%02x.%d-%08x:%1x:%08x", domain, bus, slot,
                   func, reg, size, mask);
        if (err == 7)
                return 0;
        return -EINVAL;
}

static int pcistub_device_id_add(int domain, int bus, int slot, int func)
{
        struct pcistub_device_id *pci_dev_id;
        unsigned long flags;

        pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_KERNEL);
        if (!pci_dev_id)
                return -ENOMEM;

        pci_dev_id->domain = domain;
        pci_dev_id->bus = bus;
        pci_dev_id->devfn = PCI_DEVFN(slot, func);

        pr_debug(DRV_NAME ": wants to seize %04x:%02x:%02x.%d\n",
                 domain, bus, slot, func);

        spin_lock_irqsave(&device_ids_lock, flags);
        list_add_tail(&pci_dev_id->slot_list, &pcistub_device_ids);
        spin_unlock_irqrestore(&device_ids_lock, flags);

        return 0;
}

static int pcistub_device_id_remove(int domain, int bus, int slot, int func)
{
        struct pcistub_device_id *pci_dev_id, *t;
        int devfn = PCI_DEVFN(slot, func);
        int err = -ENOENT;
        unsigned long flags;

        spin_lock_irqsave(&device_ids_lock, flags);
        list_for_each_entry_safe(pci_dev_id, t, &pcistub_device_ids,
                                 slot_list) {
                if (pci_dev_id->domain == domain
                    && pci_dev_id->bus == bus && pci_dev_id->devfn == devfn) {
                        /* Don't break; here because it's possible the same
                         * slot could be in the list more than once
                         */
                        list_del(&pci_dev_id->slot_list);
                        kfree(pci_dev_id);

                        err = 0;

                        pr_debug(DRV_NAME ": removed %04x:%02x:%02x.%d from "
                                 "seize list\n", domain, bus, slot, func);
                }
        }
        spin_unlock_irqrestore(&device_ids_lock, flags);

        return err;
}

static int pcistub_reg_add(int domain, int bus, int slot, int func, int reg,
                           int size, int mask)
{
        int err = 0;
        struct pcistub_device *psdev;
        struct pci_dev *dev;
        struct config_field *field;

        psdev = pcistub_device_find(domain, bus, slot, func);
        if (!psdev || !psdev->dev) {
                err = -ENODEV;
                goto out;
        }
        dev = psdev->dev;

        field = kzalloc(sizeof(*field), GFP_ATOMIC);
        if (!field) {
                err = -ENOMEM;
                goto out;
        }

        field->offset = reg;
        field->size = size;
        field->mask = mask;
        field->init = NULL;
        field->reset = NULL;
        field->release = NULL;
        field->clean = xen_pcibk_config_field_free;

        err = xen_pcibk_config_quirks_add_field(dev, field);
        if (err)
                kfree(field);
out:
        return err;
}

static ssize_t pcistub_slot_add(struct device_driver *drv, const char *buf,
                                size_t count)
{
        int domain, bus, slot, func;
        int err;

        err = str_to_slot(buf, &domain, &bus, &slot, &func);
        if (err)
                goto out;

        err = pcistub_device_id_add(domain, bus, slot, func);

out:
        if (!err)
                err = count;
        return err;
}
static DRIVER_ATTR(new_slot, S_IWUSR, NULL, pcistub_slot_add);

static ssize_t pcistub_slot_remove(struct device_driver *drv, const char *buf,
                                   size_t count)
{
        int domain, bus, slot, func;
        int err;

        err = str_to_slot(buf, &domain, &bus, &slot, &func);
        if (err)
                goto out;

        err = pcistub_device_id_remove(domain, bus, slot, func);

out:
        if (!err)
                err = count;
        return err;
}
static DRIVER_ATTR(remove_slot, S_IWUSR, NULL, pcistub_slot_remove);

static ssize_t pcistub_slot_show(struct device_driver *drv, char *buf)
{
        struct pcistub_device_id *pci_dev_id;
        size_t count = 0;
        unsigned long flags;

        spin_lock_irqsave(&device_ids_lock, flags);
        list_for_each_entry(pci_dev_id, &pcistub_device_ids, slot_list) {
                if (count >= PAGE_SIZE)
                        break;

                count += scnprintf(buf + count, PAGE_SIZE - count,
                                   "%04x:%02x:%02x.%d\n",
                                   pci_dev_id->domain, pci_dev_id->bus,
                                   PCI_SLOT(pci_dev_id->devfn),
                                   PCI_FUNC(pci_dev_id->devfn));
        }
        spin_unlock_irqrestore(&device_ids_lock, flags);

        return count;
}
static DRIVER_ATTR(slots, S_IRUSR, pcistub_slot_show, NULL);

static ssize_t pcistub_irq_handler_show(struct device_driver *drv, char *buf)
{
        struct pcistub_device *psdev;
        struct xen_pcibk_dev_data *dev_data;
        size_t count = 0;
        unsigned long flags;

        spin_lock_irqsave(&pcistub_devices_lock, flags);
        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (count >= PAGE_SIZE)
                        break;
                if (!psdev->dev)
                        continue;
                dev_data = pci_get_drvdata(psdev->dev);
                if (!dev_data)
                        continue;
                count +=
                    scnprintf(buf + count, PAGE_SIZE - count,
                              "%s:%s:%sing:%ld\n",
                              pci_name(psdev->dev),
                              dev_data->isr_on ? "on" : "off",
                              dev_data->ack_intr ? "ack" : "not ack",
                              dev_data->handled);
        }
        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
        return count;
}
static DRIVER_ATTR(irq_handlers, S_IRUSR, pcistub_irq_handler_show, NULL);

static ssize_t pcistub_irq_handler_switch(struct device_driver *drv,
                                          const char *buf,
                                          size_t count)
{
        struct pcistub_device *psdev;
        struct xen_pcibk_dev_data *dev_data;
        int domain, bus, slot, func;
        int err = -ENOENT;

        err = str_to_slot(buf, &domain, &bus, &slot, &func);
        if (err)
                goto out;

        psdev = pcistub_device_find(domain, bus, slot, func);

        if (!psdev)
                goto out;

        dev_data = pci_get_drvdata(psdev->dev);
        if (!dev_data)
                goto out;

        dev_dbg(&psdev->dev->dev, "%s fake irq handler: %d->%d\n",
                dev_data->irq_name, dev_data->isr_on,
                !dev_data->isr_on);

        dev_data->isr_on = !(dev_data->isr_on);
        if (dev_data->isr_on)
                dev_data->ack_intr = 1;
out:
        if (!err)
                err = count;
        return err;
}
static DRIVER_ATTR(irq_handler_state, S_IWUSR, NULL,
                   pcistub_irq_handler_switch);

static ssize_t pcistub_quirk_add(struct device_driver *drv, const char *buf,
                                 size_t count)
{
        int domain, bus, slot, func, reg, size, mask;
        int err;

        err = str_to_quirk(buf, &domain, &bus, &slot, &func, &reg, &size,
                           &mask);
        if (err)
                goto out;

        err = pcistub_reg_add(domain, bus, slot, func, reg, size, mask);

out:
        if (!err)
                err = count;
        return err;
}

static ssize_t pcistub_quirk_show(struct device_driver *drv, char *buf)
{
        int count = 0;
        unsigned long flags;
        struct xen_pcibk_config_quirk *quirk;
        struct xen_pcibk_dev_data *dev_data;
        const struct config_field *field;
        const struct config_field_entry *cfg_entry;

        spin_lock_irqsave(&device_ids_lock, flags);
        list_for_each_entry(quirk, &xen_pcibk_quirks, quirks_list) {
                if (count >= PAGE_SIZE)
                        goto out;

                count += scnprintf(buf + count, PAGE_SIZE - count,
                                   "%02x:%02x.%01x\n\t%04x:%04x:%04x:%04x\n",
                                   quirk->pdev->bus->number,
                                   PCI_SLOT(quirk->pdev->devfn),
                                   PCI_FUNC(quirk->pdev->devfn),
                                   quirk->devid.vendor, quirk->devid.device,
                                   quirk->devid.subvendor,
                                   quirk->devid.subdevice);

                dev_data = pci_get_drvdata(quirk->pdev);

                list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
                        field = cfg_entry->field;
                        if (count >= PAGE_SIZE)
                                goto out;

                        count += scnprintf(buf + count, PAGE_SIZE - count,
                                           "\t\t%08x:%01x:%08x\n",
                                           cfg_entry->base_offset +
                                           field->offset, field->size,
                                           field->mask);
                }
        }

out:
        spin_unlock_irqrestore(&device_ids_lock, flags);

        return count;
}
static DRIVER_ATTR(quirks, S_IRUSR | S_IWUSR, pcistub_quirk_show,
                   pcistub_quirk_add);

static ssize_t permissive_add(struct device_driver *drv, const char *buf,
                              size_t count)
{
        int domain, bus, slot, func;
        int err;
        struct pcistub_device *psdev;
        struct xen_pcibk_dev_data *dev_data;
        err = str_to_slot(buf, &domain, &bus, &slot, &func);
        if (err)
                goto out;
        psdev = pcistub_device_find(domain, bus, slot, func);
        if (!psdev) {
                err = -ENODEV;
                goto out;
        }
        if (!psdev->dev) {
                err = -ENODEV;
                goto release;
        }
        dev_data = pci_get_drvdata(psdev->dev);
        /* the driver data for a device should never be null at this point */
        if (!dev_data) {
                err = -ENXIO;
                goto release;
        }
        if (!dev_data->permissive) {
                dev_data->permissive = 1;
                /* Let user know that what they're doing could be unsafe */
                dev_warn(&psdev->dev->dev, "enabling permissive mode "
                         "configuration space accesses!\n");
                dev_warn(&psdev->dev->dev,
                         "permissive mode is potentially unsafe!\n");
        }
release:
        pcistub_device_put(psdev);
out:
        if (!err)
                err = count;
        return err;
}

static ssize_t permissive_show(struct device_driver *drv, char *buf)
{
        struct pcistub_device *psdev;
        struct xen_pcibk_dev_data *dev_data;
        size_t count = 0;
        unsigned long flags;
        spin_lock_irqsave(&pcistub_devices_lock, flags);
        list_for_each_entry(psdev, &pcistub_devices, dev_list) {
                if (count >= PAGE_SIZE)
                        break;
                if (!psdev->dev)
                        continue;
                dev_data = pci_get_drvdata(psdev->dev);
                if (!dev_data || !dev_data->permissive)
                        continue;
                count +=
                    scnprintf(buf + count, PAGE_SIZE - count, "%s\n",
                              pci_name(psdev->dev));
        }
        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
        return count;
}
static DRIVER_ATTR(permissive, S_IRUSR | S_IWUSR, permissive_show,
                   permissive_add);

static void pcistub_exit(void)
{
        driver_remove_file(&xen_pcibk_pci_driver.driver, &driver_attr_new_slot);
        driver_remove_file(&xen_pcibk_pci_driver.driver,
                           &driver_attr_remove_slot);
        driver_remove_file(&xen_pcibk_pci_driver.driver, &driver_attr_slots);
        driver_remove_file(&xen_pcibk_pci_driver.driver, &driver_attr_quirks);
        driver_remove_file(&xen_pcibk_pci_driver.driver,
                           &driver_attr_permissive);
        driver_remove_file(&xen_pcibk_pci_driver.driver,
                           &driver_attr_irq_handlers);
        driver_remove_file(&xen_pcibk_pci_driver.driver,
                           &driver_attr_irq_handler_state);
        pci_unregister_driver(&xen_pcibk_pci_driver);
}

static int __init pcistub_init(void)
{
        int pos = 0;
        int err = 0;
        int domain, bus, slot, func;
        int parsed;

        if (pci_devs_to_hide && *pci_devs_to_hide) {
                do {
                        parsed = 0;

                        err = sscanf(pci_devs_to_hide + pos,
                                     " (%x:%x:%x.%x) %n",
                                     &domain, &bus, &slot, &func, &parsed);
                        if (err != 4) {
                                domain = 0;
                                err = sscanf(pci_devs_to_hide + pos,
                                             " (%x:%x.%x) %n",
                                             &bus, &slot, &func, &parsed);
                                if (err != 3)
                                        goto parse_error;
                        }

                        err = pcistub_device_id_add(domain, bus, slot, func);
                        if (err)
                                goto out;

                        /* if parsed<=0, we've reached the end of the string */
                        pos += parsed;
                } while (parsed > 0 && pci_devs_to_hide[pos]);
        }

        /* If we're the first PCI Device Driver to register, we're the
         * first one to get offered PCI devices as they become
         * available (and thus we can be the first to grab them)
         */
        err = pci_register_driver(&xen_pcibk_pci_driver);
        if (err < 0)
                goto out;

        err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                 &driver_attr_new_slot);
        if (!err)
                err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                         &driver_attr_remove_slot);
        if (!err)
                err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                         &driver_attr_slots);
        if (!err)
                err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                         &driver_attr_quirks);
        if (!err)
                err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                         &driver_attr_permissive);

        if (!err)
                err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                         &driver_attr_irq_handlers);
        if (!err)
                err = driver_create_file(&xen_pcibk_pci_driver.driver,
                                        &driver_attr_irq_handler_state);
        if (err)
                pcistub_exit();

out:
        return err;

parse_error:
        printk(KERN_ERR DRV_NAME ": Error parsing pci_devs_to_hide at \"%s\"\n",
               pci_devs_to_hide + pos);
        return -EINVAL;
}

#ifndef MODULE
/*
 * fs_initcall happens before device_initcall
 * so xen_pcibk *should* get called first (b/c we
 * want to suck up any device before other drivers
 * get a chance by being the first pci device
 * driver to register)
 */
fs_initcall(pcistub_init);
#endif

static int __init xen_pcibk_init(void)
{
        int err;

        if (!xen_initial_domain())
                return -ENODEV;

        err = xen_pcibk_config_init();
        if (err)
                return err;

#ifdef MODULE
        err = pcistub_init();
        if (err < 0)
                return err;
#endif

        pcistub_init_devices_late();
        err = xen_pcibk_xenbus_register();
        if (err)
                pcistub_exit();

        return err;
}

static void __exit xen_pcibk_cleanup(void)
{
        xen_pcibk_xenbus_unregister();
        pcistub_exit();
}

module_init(xen_pcibk_init);
module_exit(xen_pcibk_cleanup);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("xen-backend:pci");